The invention relates to a display unit, and in particular to a display unit applied in a display panel.
FIG. 1 is a schematic diagram of a panel of a conventional organic light emitting display (OLED) device. As shown in FIG. 1, a panel 1 comprises a data driver 10, a scan driver 11, and a display array 12. The data driver 10 controls a plurality of data lines D1 to Dn and the scan driver 11 controls a plurality of scan lines S1 to Sm. The display array 12 is formed by interlaced data lines D1 to Dn and scan lines S1 to Sm. Each interlaced data line and scan line corresponds to one display unit, for example, interlaced data line D1 and scan line S1 correspond to display unit 100. As with any other display unit, the equivalent circuit of the display unit 100 comprises a switch transistor T10, a storage capacitor. C10, a driving transistor T11, and a light-emitting diode D10.
The scan driver 11 sequentially outputs scan signals to scan lines S1 to Sm to turn on the switch transistors within all display units corresponding to one row and turn off the switch transistors within all display units corresponding to all other rows. The data driver 10 outputs data signals with gray-scale values to the display units corresponding to one row through the data lines D1 to Dn according to prepared image data but not yet displayed. For example, when the scan driver 11 outputs a scan signal to the scan line S1, the switch transistor T10 is turned on, and the data driver 10 outputs a corresponding data signal SD to the display unit 100 through the data line D1. At this time, a voltage at a node N10 is equal to voltage vdata of the data signal SD. The driving transistor T11 is turned on according to the voltage at the node N10 and provides a driving current Id to drive the LED D10 to emit light.
In an OLED device, with the increment of the light-emitting time of the LED D10, the brightness of the LED D10 is lowered for the same data signal SD. In other words, when each display unit of the panel 1 displays an image of the same brightness, the display units, lit for a long time, have lower brightness than the display units, only recently lit. Thus, brightness of the image on panel 1 is not uniform resulting in sticking image.